To change the oil on a Mk4 you have to remove a metal cover with about 9 off 12mm AF bolts and 2 off 10mm AF bolts. You loose the will to live half way through removing the bolts.
The two rear bolt holes have to be slipped above the rear black plastic cover.
We got it wrong when we replaced it as we needed in there to apply underseal to the front subframe.
The filter on the Mk4 is half the size of the Mk3 filter see here, the off white filter is off a Mk3.
It is much easier to gain access to the filter on the Mk4.
It needs a 68mm 14 flute cup wrench to remove it.
The Mk4 drain plug needs a 8mm allen key rather than a 17mm spanner. They both use the same crush washer.
A great and informative post. One for the future…
Great post, thanks . So what happens in the future for cars several years old when those 14 bolts seize and snap off when you try to undo them…
Some copperslip grease is in order methinks!
If you notice the colour of the bolts (greenish) there is some kind of treatment to them which may help prevent corrosion. It’s one to monitor and if necessary copperslip etc in time.
Interestingly the construction and fitment of the plate suggest it plays a part in the torsional rigidity of the vehicle.
I have done lots of 2006 Mk3’s recently with 12mm AF bolts on their inspection plate to give access to the oil filter.
I have had no problem at all with breaking the bolts.
Now lots of 10mm AF M6 Mk2 undershield bots break but how often are these removed every 5 years?
The two bolts that may have a problem are the twe 10mm AF at the back at the black undertray.
Therefore a yearly removal to do an oil change and a touch of copperslip should keep that possibility at bay.